Multifunctional polyindole/nanometal-oxide composites: Optoelectronic and charge transport properties

This study reports the electronic and optoelectronic properties of polyindole (PIN) based nanometal-oxide composites synthesized by a chemical polymerization method. Optical analyses indicated that molybdenum(VI)oxide (MoO3) and tungsten(VI)-oxide (WO3) nanoparticles increased both the optical band gap and the fluorescence emission intensity of PIN. In addition, the lower conduction band edge values of MoO3 (-0.24 eV) and WO3 (-0.35 eV) indicated electron migration from these metal oxides to the PIN (0.76 eV). The degree of crystallinity of PIN increased from approximately 25% to 40% with the addition of MoO3 and to 65% for WO3. The interaction between nanoparticles and chain segments increased the onset degradation temperature of PIN by about 45 degrees C. The charge transport mechanism of PIN and its composites was consistent with the correlated barrier hopping (CBH) model. The required activation energy for hopping of the charge carriers in the PIN matrix increased from 0.17 to 0.19 and 0.23 eV with the addition of the MoO3 and WO3 nanoparticles, respectively, pointing to an increase in the hopping distance of the charge carriers. The experimental analyses indicated that the PIN/MoO3 and PIN/WO3 composites could be used as semiconductor materials in electronics and optoelectronics applications.